Coupled resonant cavity surface-emitting laser

Abstract

The CRCSEL comprises a single-mode optical gain structure and an optically-resonant cavity. The single-mode optical gain structure is structured to generate excitation light having a wavelength and a direction. The optically-resonant cavity is optically coupled to the single-mode optical gain structure and is structured to emit an output light beam in a direction substantially orthogonal to the excitation light. The change in light direction provided by the optically-resonant cavity enables the output light beam to emit from a surface while allowing the excitation light to be generated in a large, high-gain single-mode optical gain structure.

1. A surface-emitting laser, comprising a layer structure, the layer structure comprising:
 a single-mode optical gain structure structured to generate excitation light having a wavelength and a direction, the optical gain structure surrounded by an evanescent field associated with the excitation light; and  
 an optically-resonant cavity located alongside the single-mode optical gain structure not intersecting therewith, the optically-resonant cavity optically coupled by the evanescent field to the single-mode optical gain structure to receive part of the excitation light therefrom, the optically-resonant cavity structured to emit an output light beam in a direction orthogonal to the direction of the excitation light.  
 
     
     
       2. The surface-emitting laser of  claim 1 , in which the single-mode optical gain structure includes an elongate optical waveguide through which the excitation light propagates. 
     
     
       3. The surface-emitting laser of  claim 2 , in which the waveguide includes and active region in which the excitation is generated. 
     
     
       4. The surface-emitting laser of  claim 3 , in which the single-mode optical gain structure additionally includes reflective elements operative to impose a single mode on the excitation light. 
     
     
       5. The surface-emitting laser of  claim 3 , in which the single-mode optical gain structure comprises one-dimensional distributed Bragg reflectors separated from one another along the length of the waveguide. 
     
     
       6. The surface-emitting laser of  claim 3 , in which the single-mode optical gain structure comprises a diffraction grating disposed along the length of the waveguide. 
     
     
       7. The surface-emitting laser of  claim 1 , in which the optically-resonant cavity includes:
 a cavity-defining structure of a cavity-defining structure material having a first dielectric constant; and p 1  a material filling interstices in the cavity-defining structure, the material having a second dielectric constant different from the first dielectric constant.  
 
     
     
       8. The surface-emitting laser of  claim 1 , in which the optically-resonant cavity is structured to emit the output light beam with an axially symmetric radiation pattern. 
     
     
       9. The surface-emitting laser of  claim 1 , in which the layer structure additionally comprises:
 a substrate of gallium arsenide; and  
 a layer of embedding material in which the optically-resonant cavity is located, the embedding material including aluminum arsenide.  
 
     
     
       10. The surface-emitting laser of  claim 1 , in which the layer structure additionally comprises:
 a substrate of indium phosphide; and  
 a layer of embedding material in which the optically-resonant cavity is located, the embedding material including indium gallium arsenide phosphide.  
 
     
     
       11. The surface-emitting laser of  claim 1 , in which the layer structure additionally comprises at least one additional optically-resonant cavity optically coupled to the single-mode optical gain structure, each of the at least one optically-resonant cavity structured to emit a respective output light beam in a direction substantially orthogonal to the excitation light. 
     
     
       12. The surface-emitting laser of  claim 1 , in which the optically-resonant cavity is located alongside the single-mode optical gain structure and separated therefrom by a distance of less than one wavelength of the excitation light. 
     
     
       13. A surface-emitting laser, comprising:
 a single-mode optical gain structure structured to generate excitation light having a wavelength and a direction; and  
 an optically-resonant cavity optically coupled to the single-mode optical gain structure to receive part of the excitation light therefrom, the optically-resonant cavity structured to emit an output light beam in a direction orthogonal to the excitation light, the optically-resonant cavity comprising: 
 a cavity-defining structure of a cavity-defining structure material having a first dielectric constant, the cavity-defining structure comprising: 
 a reflective cylinder of the cavity-defining structure material, the reflective cylinder having an axis of rotational symmetry parallel to the output light beam; and  
 reflective plates arrayed along the axis of rotational symmetry of the reflective cylinder, the reflective plates intersecting the reflective cylinder,  
 
 a material filling interstices in the cavity-defining structure, the material having a second dielectric constant different from the first dielectric constant.  
 
 
     
     
       14. The surface-emitting laser of  claim 13 , in which:
 the reflective cylinder is a first reflective cylinder; and  
 the cavity-defining structure additionally comprises at least one additional reflective cylinder arranged concentrically with the first reflective cylinder and intersecting with the reflective plates.  
 
     
     
       15. The surface-emitting laser of  claim 13 , in which:
 the reflective cylinder and a pair of the reflective plates collectively define a central cavity; and  
 fewer of the reflective plates are disposed along the axis of rotational symmetry in one direction relative to the central cavity than in the opposite direction.  
 
     
     
       16. A method generating coherent light, the method comprising:
 providing a layer structure, the layer structure comprising an optically-resonant cavity;  
 externally of the layer structure, generating excitation light having a single optical mode in a direction parallel to a major surface of the layer structure, the excitation light having an evanescent field associated therewith;  
 coupling part of the excitation light to the optically-resonant cavity via the evanescent field; and preferentially emitting the received excitation light from the optically-resonant cavity in a direction orthogonal to the major surface.  
 
     
     
       17. The method of  claim 16 , in which generating the excitation light includes generating the excitation light by stimulated emission. 
     
     
       18. The method of  claim 16 , in which preferentially emitting the received excitation light includes emitting the received excitation light in an axially asymmetric radiation pattern. 
     
     
       19. The method of  claim 18 , in which, in providing an optically-resonant cavity, an optically-resonant cavity structured to be optically resonant at the wavelength of the excitation light and having an axially-asymmetric containment characteristic is provided. 
     
     
       20. The method of  claim 19 , in which the method additionally comprise locating the optically-resonant cavity at a distance from the excitation light of less than the wavelength of the excitation light. 
     
     
       21. The method of  claim 16 , in which generating the excitation light includes:
 providing one-dimensional distributed Bragg reflectors; and  
 using the one-dimensional distributed Bragg reflectors to impose the single optical mode on the excitation light.  
 
     
     
       22. The method of  claim 16 , in which generating the excitation light includes:
 providing a diffraction grating; and  
 using the diffraction grating to impose the single optical mode on the excitation light.